Preparation of electrochemically exfoliated graphene sheets using DC switching voltages
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Among various methods to produce graphene sheets, electrochemical exfoliation has been regarded as an effective method for the mass production of high-quality graphene sheets because of its simplicity and environmental friendliness. However, conventional electrochemical exfoliation has a disadvantage of accumulating intercalating ions at graphite interlayers owing to the use of a constant voltage. In this study, we developed a DC switching technique to achieve more efficient intercalation of ions than that in the conventional method. In the DC switching method, positive and negative voltages are successively applied to release the accumulated intercalating ions. By testing various conditions, we found the optimum switching time to produce high-quality graphene sheets with the highest yield rate and the highest electrical conductivity. As a result, the graphene sheets using this DC switching technique showed 85% higher yield rate, 193% higher electrical conductivity, 160% larger area, and 25% thinner thickness than those obtained when using a constant DC method. We believe that this DC switching technique can be used for large-scale production of high-quality graphene sheets.
KeywordsGraphene Electrochemical exfoliation DC switching technique Intercalating ions Electrical conductivity
This work was supported by the National Research Foundation (NRF) of Korea grant funded by the Ministry of Science, ICT and Future Planning (2016M3A7B4021149 and 2018R1A2A2A15020973). Also, the authors are grateful to the Center for Research Facilities at the Chonnam National University for the assistance in chemical analyses (AFM, Raman and XPS).
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Conflict of interest
No potential conflict of interest relevant to this article is reported.
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